Saturated sandstone viscoelastic behavior analysis by stress-strain approach
Xi Daoying1, Yi Liangkun2, Xi Jun3, Du Yun1
1. Mengcheng National Geophysical Observatory,School of Earth and Space Science,University of Science and Technology of China,Hefei,Anhui 230026,China;
2. GRI,BGP Inc,CNPC,Zhuozhou,Hebei 072750,China;
3. School of Mechanical Engineering,Beijing Institute of Petrochemical Technology,Beijing 102671,China
Abstract：Experiments are performed by Metravib Dynamic Mechanical Analyzer(DMA+450) under sine wave loading.The static load is fixed at 100N,and the dynamic load of the sine wave is 60N so that the total loading force is controlled under yield stress.Temperature is controlled between-30℃ and 150℃ with 1.5℃ per minute heating.The frequency range is from 1 to 1000Hz.Pump-oil saturated arkoses and Pengshan sandstones are tested under uniaxial cyclic loading to study attenuation,Young's modulus and elastic wave velocity variations with temperature or frequency.The attenuation peak shifts to higher temperatures when the frequency increases,which coincides with thermal relaxation regularities and Arrhenius relation.Experiments show similar thermal relaxation regularities to the low frequency resonance standing wave experiments.Thus the thermal relaxation regularities generally exist for saturated porous rocks.Experiments also show that the Young's modulus and velocity increase with frequency and decrease when temperature increases.There is obvious strong frequency dispersion,and the dispersion decreases when temperature increases.
